Efficacy of extended pirlimycin therapy for treatment of experimentally induced Streptococcus uberis intramammary infections in lactating dairy cattle

Streptococcus uberis is an important cause of mastitis in dairy cows throughout the world, particularly during the dry period, around the time of calving, and during early lactation. Strategies for controlling S. uberis mastitis have not received adequate research attention and are therefore poorly defined and inadequate. Objectives of the present study were to evaluate the efficacy of extended therapy regimens with pirlimycin for treatment of experimentally induced S. uberis intramammary infections in lactating dairy cows during early lactation and to evaluate the usefulness of the S. uberis experimental infection model for evaluating antimicrobial efficacy in dairy cows. The efficacy of extended pirlimycin intramammary therapy regimens was investigated in 103 mammary glands of 68 dairy cows that became infected following experimental challenge with S. uberis during early lactation. Cows infected with S. uberis in one or both experimentally challenged mammary glands were randomly allocated to three groups, representing three different treatment regimens with pirlimycin, including 2-day (n = 21 cows, 31 mammary quarters), 5-day (n = 21 cows, 32 quarters), and 8-day (n = 26 cows, 40 quarters). For all groups, pirlimycin was administered at a rate of 50 mg of pirlimycin hydrochloride via intramammary infusion. A cure was defined as an experimentally infected mammary gland that was treated with pirlimycin and was bacteriologically negative for the presence of S. uberis at 7, 14, 21, and 28 days after treatment. Experimental S. uberis intramammary infections were eliminated in 58.1% of the infected quarters treated with the pirlimycin 2-day regimen, 68.8% for the 5-day regimen, and 80.0% for the 8-day regimen. Significant differences (P <.05) in efficacy were observed between the 2-day and 8-day treatment regimens. The number of somatic cells in milk decreased significantly following therapy in quarters for which treatment was successful in eliminating S. uberis. However, there was no evidence to suggest that extended therapy with pirlimycin resulted in a greater reduction in somatic cell counts in milk than the 2-day treatment. The S. uberis experimental infection model was a rapid and effective means of evaluating antimicrobial efficacy during early lactation at a time when mammary glands are highly susceptible to S. uberis intramammary infection.     

复方阿莫西林乳房注入剂对临床型奶牛乳房炎的治疗效果

为评价复方阿莫西林乳房注入剂对泌乳期奶牛临床型乳房炎的治疗效果,在甘肃某两个牛场选择70头自然发生的临床型乳房炎奶牛进行临床试验.将患病奶牛随机分为试验组(n=36头)和对照组(n=34头).试验用药和对照用药分别为郑州百瑞动物药业有限公司和齐鲁动物保健品有限公司提供的复方阿莫西林乳房注入剂.每个感染乳区注入3 g药物...     

Successful treatment of recurrent subclinical mastitis in cows caused by enrofloxacin resistant bacteria by means of the sequential intramammary infusion of enrofloxacin HCl-2H2O and ceftiofur HCl: a clinical trial

BackgroundRecurrent subclinical mastitis (RScM) due to resistant bacteria has low clinical and bacteriological cure rates, often requiring the culling of cows. The sequential intra-mammary administration of enrofloxacin hydrochloride-dihydrate (enro-C) followed by ceftiofur HCl may be useful for treating these cases.ObjectivesThis study assessed the bacteriological and clinical cure-efficacies of the sequentially intramammary administration of enro-C, followed by ceftiofur HCl to treat RScM in Holstein/Friesian cows.MethodsThis trial was conducted in a herd with a high prevalence of RScM, and 20 Holstein/Friesian cows were included: 45% suffering subclinical mastitis and 38.9% of the mammary quarters affected. Twenty-nine bacterial isolates in vitro resistant to enro-C were obtained (coagulase-negative Staphylococcus spp, 55.2%; Staphylococcus aureus, 27.6%; Escherichia coli, 6.9%; Streptococcus uberis, 6.9%; Corynebacterium bovis, 3.4%). Polymerase chain reaction-isolated the following genes linked to enro-C resistance: chromosomal (gyrA) and plasmid (aac(6'')-lb-cr). The treatments were as follows: twice-daily intramammary infusions of enro-C (300 mg/10 mL) for 5 days. Cows clinically considered treatment failures were also treated with intramammary ceftiofur (125 mg/10 mL, twice daily for 5 days. The clinical and bacteriological cure rates were carried out when completing each treatment phase and at 14 and 21 days, aided by a California mastitis test, somatic cell count, and failure to identify the initially causative bacteria.ResultsEnro-C achieved 65% clinical and bacteriological cure rates, and 100% cure rates were obtained after the rescue treatment with ceftiofur HCl.ConclusionsOutstanding clinical and bacteriological cure rates in cows affected by RScM were achieved with the consecutive intramammary infusions of enro-C, followed by ceftiofur HCl.     

Efficacy of extended pirlimycin hydrochloride therapy for treatment of environmental Streptococcus spp and Staphylococcus aureus intramammary infections in lactating dairy cows

Fifty-one chronically infected lactating dairy cows were used to evaluate the efficacy of extended pirlimycin therapy regimens for treatment of intramammary infections by environmental Streptococcus spp and Staphylococcus aureus. Cows (n = 47) with one or more infected mammary quarters were blocked by parity and randomly allocated to one of three groups for treatment with pirlimycin (50 mg/mammary quarter) as follows: one treatment per day for 2 days (n = 36 infected mammary quarters); one treatment per day for 5 days (n = 36 infected mammary quarters); and one treatment per day for 8 days (n = 20 infected mammary quarters). Four cows with nine infected mammary quarters were included as untreated controls. Milk samples from each mammary quarter were collected 7 days before treatment, immediately before treatment, and weekly for 4 weeks after the final treatment for microbiological evaluation. A bacteriologic cure was defined as a treated, infected quarter that was bacteriologically negative for the presence of previously identified bacteria at weekly intervals after treatment. Efficacy of pirlimycin therapy against intramammary infections caused by environmental Streptococcus spp and S. aureus was 44.4%, 61.1%, and 95.0% for the 2-, 5-, and 8-day treatment regimens, respectively. None of the infections in the untreated control quarters was cured. Significant differences in efficacy were detected between all pirlimycin groups and the untreated control group, between the 8- and 2-day treatment regimens, and between the 8-day and 5-day treatment regimens (P < or = .05). Results of this study indicate that extended pirlimycin therapy was effective in eliminating intramammary infections caused by environmental streptococci and S. aureus in lactating dairy cows.     

Elimination kinetics of ceftiofur hydrochloride after intramammary administration in lactating dairy cows

OBJECTIVE: To determine the elimination kinetics of ceftiofur hydrochloride in milk after intramammary administration in lactating dairy cows. DESIGN: Prospective study. ANIMALS: 5 lactating dairy cows. PROCEDURE: After collection of baseline milk samples, 300 mg (6 mL) of ceftiofur was infused into the left front and right rear mammary gland quarters of each cow. Approximately 12 hours later, an additional 300 mg of ceftiofur was administered into the same mammary gland quarters after milking. Milk samples were collected from each mammary gland quarter every 12 hours for 10 days. Concentrations of ceftiofur and its metabolites in each milk sample were determined to assess the rate of ceftiofur elimination. RESULTS: Although there were considerable variations among mammary gland quarters and individual cows, ceftiofur concentrations in milk from all treated mammary gland quarters were less than the tolerance (0.1 microg/mL) set by the FDA by 168 hours (7 days) after the last intramammary administration of ceftiofur. No drug concentrations were detected in milk samples beyond this period. Ceftiofur was not detected in any milk samples from nontreated mammary gland quarters throughout the study. CONCLUSIONS AND CLINICAL RELEVANCE: Ceftiofur administered by the intramammary route as an extra-label treatment for mastitis in dairy cows reaches concentrations in milk greater than the tolerance set by the FDA. Results indicated that milk from treated mammary gland quarters should be discarded for a minimum of 7 days after intramammary administration of ceftiofur. Elimination of ceftiofur may be correlated with milk production, and cows producing smaller volumes of milk may have prolonged withdrawal times.     

Efficacy of a 5-day extended therapy program during lactation with cephapirin sodium in dairy cows chronically infected with Staphylococcus aureus

This study determined the efficacy of a 5-day extended therapy with cephapirin sodium in dairy cows chronically infected with Staphylococcus aureus. Chronically infected cows selected from 14 dairy herds in the St-Hyacinthe region, Québec were randomly allocated to a group of 31 cows treated for 5 consecutive days with 200 mg of cephapirin per quarter BID or a group of 30 untreated control cows. Bacteriological cure was determined by 3 negative bacterial cultures at 10, 24, and 31 days after treatment. The cow cure rates were 25.8% (8/31) in the treated cows and 3.3% (1/30) in the control group (P = 0.013). The quarter cure rates at first sampling post-treatment were 77.6% (38/49) and 18% (9/50) in the treated and the control groups, respectively (P < 0.0001). A 5-day extended therapy with cephapirin is effective in treating cows chronically infected with S. aureus.     

A comparative efficacy trial between cefuroxime and cloxacillin as intramammary treatments for clinical mastitis in lactating cows on commercial dairy farms

AIMS: To assess the efficacy of a commercial intramammary preparation containing cefuroxime as a treatment for clinical mastitis in lactating dairy cows. METHODS: Clinical mastitis cases (n=440) were identified during early to mid lactation on 36 seasonally-calving commercial dairy herds in south-western Victoria, Australia, that ranged in size from 140 to 550 cows. A milk sample for bacterial culture was collected from each affected quarter prior to treatment. Cases were treated using a commercial intramammary antibiotic product containing either 250 mg cefuroxime or 200 mg cloxacillin, according to the manufacturer's recommendations, and the recommended milk with-holding period was observed. The assessment of clinical cure of each case was made by the farm owner/manager at the end of the milk with-holding period. Post-treatment milk samples were taken from clinically cured quarters at each of three consecutive milkings, commencing 7 days after the end of the milk with-holding period and submitted for bacterial culture. RESULTS: Pathogenic bacteria were isolated from 252/416 (60.6%) pre-treatment milk samples submitted from eligible cases. Streptococcus uberis was the most frequent isolate, being cultured from 31.7% of cases. Staphylococcus aureus was isolated from 18.3% of pre-treatment samples, and Esherichia coli from 7.0%. The clinical cure rate for all eligible cases was 81.7%. There was no significant difference in clinical cure rates between cases treated with cefuroxime (186/225=82.7%) and cases treated with cloxacillin (154/191=80.6%). The trial had 80% power to detect a significant difference if the actual cure rates differed by at least 12.6%. There was a superior clinical response rate (p=0.04) for mastitis cases from which E. coli was isolated that were treated with cefuroxime (18/19=95%) compared with cloxacillin 6/10=60%), but case numbers were low (n=29). The overall bacteriological cure rate for the trial was 70% (69/98 cases assessed). There was no significant difference (p=0.27) in bacteriological cure rate between cases treated with cefuroxime (42/56=75%) and cases treated with cloxacillin (27/42=64%). CONCLUSIONS: This trial demonstrated that cefuroxime was an effective intramammary treatment for clinical mastitis and had similar clinical and bacteriological cure rates to cloxacillin, an accepted industry-standard product. Activity against Gram-negative and Gram-positive bacteria was demonstrated for cefuroxime which, along with the economic benefits of less discarded milk compared with other antibiotic preparations, indicated that cefuroxime is likely to be an appropriate intramammary antibiotic for the treatment of clinical mastitis in commercial dairy herds during early to mid lactation in Victoria, Australia.     

Efficacy of vaccination and antimicrobial treatment to eliminate chronic intramammary Staphylococcus aureus infections in dairy cattle

OBJECTIVE: To determine whether a combination of vaccination and extended intramammary antimicrobial treatment would eliminate chronic intramammary Staphylococcus aureus infections in lactating dairy cows. DESIGN: Randomized controlled clinical trial. ANIMALS: 50 dairy cows with chronic mastitis caused by S aureus. PROCEDURE: Cows were identified and paired within herd on the basis of days in milk, lactation number, milk production, and numbers of quarters infected. Treated cows (n=20) received 3 doses of a polyvalent S aureus bacterin on days 1, 15, and 21 of the study along with intramammary administration of pirlimycin in all 4 quarters once daily for 5 treatments (days 16 to 20). Control cows (n=23) received no treatment. Follow-up samples for bacteriologic culture were collected for at least 3 months after treatment to determine treatment success rates. RESULTS: Significantly more S aureus infections were eliminated from treated cows (8/20 [40%]), compared with control cows (2/23 [9%]). The proportion of infected quarters that yielded negative results throughout the follow-up period was also significantly higher in treated cows (13/28 [46%]) than in control cows (2/41 [5%]). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that a combination of vaccination and antimicrobial treatment can be successful in eliminating some cases of chronic intramammary S aureus infections in dairy cattle. However, it is important to consider extended treatment protocols carefully because many cows are likely to remain infected with S aureus despite treatment and vaccination.     

Efficacy of specific egg yolk immunoglobulin (IgY) to bovine mastitis caused by Staphylococcus aureus

The objective of this study was to estimate the efficacy of specific egg yolk immunoglobulin (IgY) to bovine mastitis caused by Staphylococcus aureus. Eighteen lactating cows with clinical mastitis and 18 lactating cows with experimental mastitis (1 quarter per cow) were randomly assigned to three treatments: IgY (20mg/ml) infusion, penicillin (100mg/ml) infusion and no infusion. Treatments for clinical mastitis and experimental mastitis were performed by a 6-day course of intramammary infusion with a dosage of 10ml at an interval of 12h. Milk samples were collected at morning milking time for testing color, clot, somatic cell counts (SCC) and bacterial count. For most of the cows treated with IgY and penicillin, the milk color and clot recovered to normal form during the therapy course. The milk SCCs and bacterial counts of treated cows decreased compared to those of untreated cows (p<0.05). The cure rates by IgY for experimental and clinical mastitis were 83.3% and 50%, respectively, and those by penicillin were 66.7% and 33.3%, respectively. These results showed the potential of specific IgY to be an alternative therapy for mastitis caused by S. aureus.     

Intramammary treatment of clinical mastitis of dairy cows with a combination of lincomycin and neomycin, or penicillin and dihydrostreptomycin

AIM: To compare clinical and bacteriological cure rates of clinical mastitis following treatment with intramammary preparations containing either lincomycin and neomycin or penicillin and dihydrostreptomycin. METHODS: Cases of clinical mastitis were sourced from four seasonal-calving dairy herds in the central Waikato region of New Zealand during the first 120 days of lactation. Affected quarters were infused three times at 12 h intervals with either 333 mg lincomycin plus 100 mg neomycin (lin/neo; 197 glands),or 1,000 mg penicillin plus 500 mg dihydrostreptomycin (pen/DHS; 207 glands). Milk samples were collected for bacteriology from each quarter immediately before and approximately 21 days after initiation of treatment. Additionally, a composite milk sample from each cow was collected, on average, 54 days after enrolment for assessment of milk yield, composition and somatic cell count (SCC). The probability of bacterial cure was initially analysed using Chi-squared analysis, and factors that were associated (p<0.2) were offered to a reverse stepwise logistic regression model. Continuous variables (e.g. milk solids production and log10 SCC) were analysed using general linear models. RESULTS: A total of 404 quarters diagnosed with clinical mastitis, from 282 cows in the first 120 days of lactation, were included. Streptococcus uberis, coagulase-negative staphylococci and Staphylococcus aureus were isolated from 56.5%, 18.8% and 10.0% of the bacteriologically positive quarters. There was no difference in the bacteriological cure rate (76.7% vs 76.7%, OR=0.94; p>0.8), the log10 SCC (2.1, SE 0.1, vs 2.0, SE 0.1; p>0.3) or milk production (1.2, SE 0.1, vs 1.2, SE 0.1, kg milksolids/cow/day; p>0.7) between lin/neo vs pen/DHS treatments, respectively. However, the proportion of cows re-treated following initial treatment was higher for the lin/neo compared to pen/DHS-treated group (16.3% vs 5.2%, OR=3.46; p<0.05). CONCLUSIONS: No difference in bacteriological cure rate, milk production or SCC was evident between lin/neo and pen/DHS intramammary treatments for clinical mastitis in dairy cows during the first 120 days of lactation. KEYWORDS: Dairy cow, mastitis, intramammary, antibiotic, treatment, somatic cell count.     

Efficacy of conventional and extended intra-mammary treatment of persistent sub-clinical mastitis with cefquinome in lactating dairy cows

The objectives of the present study were to evaluate the efficacy of intra-mammary-administered cefquinome for the treatment of sub-clinical mastitis in lactating dairy cows and to determine if extended therapy would enhance treatment efficacy. Seventy-three Holstein dairy cows from a single farm with 150 infected quarters were enrolled in the study. Infected cows were allocated randomly to one of three treatment regimens: (1) conventional (standard) regimen: 75 mg of cefquinome administered three times at 16-h intervals (25 infected cows, 52 intra-mammary infections (IMI)), (2) extended regimen: 75 mg of cefquinome administered six times at 16-h intervals (26 infected cows, 58 IMI) and (3) negative untreated control group (22 cows, 40 IMI). Most IMI were caused by coagulase-negative staphylococci, streptococci other than Streptococcus agalactiae and coliforms. The overall bacteriological cure (BC) rates for sub-clinical IMI were 84.61%, 91.37% and 20% for the conventional, extended and the control groups, respectively, indicating a higher BC rate for the treated groups than the control group (P < 0.001). Significant differences in somatic cell count (SCC) were detected between the treated versus the control group (P < 0.001). No differences, concerning the BC rate or SCC, were observed between the extended and the conventional groups. Although fat and protein percentages increased in the treated groups, there were no significant differences in post-treatment milk production between the groups. Results of this study indicate that cefquinome therapy was effective in reducing SCC and eliminating sub-clinical IMI in lactating dairy cows, but extended therapy did not enhance treatment efficacy.     

Clinical and bacteriological response to treatment of clinical mastitis with one of three intramammary antibiotics

AIM: To compare the proportions of clinical and bacteriological cure of glands of dairy cows diagnosed with clinical mastitis, following treatment with one of three different intramammary antibiotic preparations. METHODS: Cows from dairy cow herds (n=28) across New Zealand which were diagnosed with clinical mastitis in one or more glands at any stage of lactation were randomly assigned at the cow level within sequentially presented groups of three animals to be treated with one of three intramammary antibiotics. The treatments were 1 g procaine penicillin, 0.25 g cefuroxime, and a combination of 1 g procaine penicillin and 0.5 g dihydrostreptomycin (DHS). All treatments were infused on three occasions at 12-hourly intervals. Duplicate milk samples were collected for bacteriology before initial treatment, and 21-42 days later. Logistic regression or generalised linear mixed models were used to analyse the proportion of cows or quarters retreated for mastitis within 30 days of initial treatment ('clinical treatment failure'), and the proportion of glands from which bacteria were isolated initially but from which the same bacterial species was not re-isolated ('bacteriological cure'). RESULTS: The annual herd average cumulative incidence rate of clinical mastitis was 12.7 cases/100 cows. The incidence rate was higher in young (2-year-old) and old (> or = 9-year-old) cows relative to 3- and 4-year-old cows, and was higher in Friesian than Jersey or crossbred cows. Streptococcus uberis was the pathogen most commonly isolated, and its relative prevalence declined with time postpartum. Cows treated with cefuroxime were more likely (p<0.01) to be re-treated for clinical mastitis in the 30 days after initial treatment than cows treated with procaine penicillin or procaine penicillin and DHS. Bacteriological cure occurred in 74% of treated glands and there was no difference in the proportion of cures among the treatments (p=0.4). The proportion of cures was lower when treatment occurred 28-72 days after calving (p<0.01) and if a major pathogen was isolated (p<0.001). CONCLUSIONS AND CLINICAL RELEVANCE: There was no benefit in terms of clinical or bacteriological cure rate in treating clinical mastitis cases with the combination of procaine penicillin and DHS compared to treatment with procaine penicillin alone. The proportion of clinical mastitis cases re-treated differed among herds, and more cows treated with cefuroxime were retreated within 30 days of initial treatment. However, the bacteriological cure proportion was the same among the treatments. Cure proportions were lower in cows from which major mastitis pathogens were isolated and when treatment commenced 28-72 days after calving.     

Effects of intramammary infusion of Bifidobacterium breve on mastitis pathogens and somatic cell response in quarters from dairy cows with chronic subclinical mastitis

The present study assessed the effects of intramammary infusion of Bifidobacterium breve (B. breve) on mastitis‐causing pathogens and on the somatic cell counts (SCC) in lactating cows with chronic subclinical mastitis. The bacteriological cure rates of 42 quarters from 42 cows infected with Staphylococcus aureus, Corynebacterium bovis, coagulase‐negative staphylococci, and environmental streptococci were 18.2% (2/11), 14.3% (1/7), 58.8% (10/17), and 28.6% (2/7), respectively, on day 14 after B. breve infusion. In a second trial, B. breve was infused into 18 quarters from 18 cows with chronic subclinical mastitis from which pathogens had not been isolated; the rates of quarters showing SCC > 50 × 10⁴ cells/ml prior to B. breve infusion that decreased to < 30 × 10⁴ cells/ml after infusion were significantly (p < .01) increased to 61.1% (11/18) on day 14 compared to that prior to infusion (0/18). The intramammary infusion of B. breve appears to be a non‐antibiotic approach for elimination of minor pathogens and decreasing SCC in quarters with chronic subclinical mastitis in dairy cows.     

奶牛临床型乳房炎Nisin抗菌肽治疗后日产奶量及主要乳成分的变化

选取临床型乳房炎自然发病病例9头,乳房内灌注乳酸链球菌素(Nisin)进行治疗,通过检测日产奶量以及停药后2,7,14,21 d的主要乳成分指标,确定Nisin乳房灌注剂对临床型乳房炎病例泌乳性能的影响情况。结果显示,乳房内灌注Nisin后患病乳区乳腺组织得到一定程度的修复,日产奶量逐渐恢复,停药后8 d的日产奶量与发病前6 d相比,平均降幅2.5 kg。治愈后患病乳区牛奶乳脂肪、乳蛋白、乳糖和非脂乳固体含量都呈现上升趋势,但与同期相比,略低于非用药乳区混合牛奶;其中,乳糖含量增加幅度较快,除停药后2 d的治疗乳区外,乳糖含量均在4.7%以上,提示奶牛乳房炎病例经Nisin乳房灌注治疗后,受损乳腺组织修复较快,乳腺上皮细胞合成乳成分的能力大幅度提高。由此可见,Nisin对奶牛临床型乳房炎具有良好的治疗作用。     

国产盐酸吡利霉素乳区注入剂治疗奶牛乳房炎的效果观察

本试验通过与进口盐酸吡利霉素的对比,研究确定了国产盐酸吡利霉素对葡萄球菌、链球菌性乳房炎的治疗效果,旨在为药物的临床应用提供依据。结果表明,隐性乳房炎试验组和对照组的总有效率均为100%(12/12和10/10),治愈率分别为83.33%(10/12)和90%(9/10),平均用药次数为1.65次和1.5次;临床型乳房炎试验组的25mg组、50mg组、75mg组和对照组的总有效率分别为50%(5/10)、75%(10/12)、85.71%(12/14)和80%(8/10);治愈率为30%(3/10)、58.33%(7/12)、64.29%(9/14)和60%(6/10);平均用药次数为6次、4.9次、5.57次和5次。经卡方检验,试验组和对照组之间治愈率、有效率均无显著差异。可以得出国产盐酸吡利霉素对葡萄球菌和链球菌引起的隐性乳房炎和临床型乳房炎,均有良好的治疗效果。     

复方阿莫西林乳房注入剂治疗临床型奶牛乳房炎的疗效观察

为评价复方阿莫西林乳房注入剂治疗临床型奶牛乳房炎的疗效,在北京某牛场选择25头(48个乳区)临床型乳房炎患牛进行疗效观察。将临床型乳房炎患牛随机分为受试药物组(25个乳区)和对照药物组(23个乳区)。受试药物组患病乳区灌注复方阿莫西林乳房注入剂,对照药物组则灌注速诺LC。采用临床学与细菌学治愈率相结合的方法进行药效学评价。复方阿莫西林乳房注入剂治疗临床型乳房炎的临床学治愈率为68.0%,细菌学治愈率为83.3%,而速诺LC治疗组分别为69.6%、81.8%,两者治疗效果无显著性差异(P>0.05)。结果表明,复方阿莫西林乳房注入剂对临床型乳房炎具有较好的治疗效果。     

盐酸吡利霉素治疗奶牛乳房炎临床药效学及对乳品质影响的研究

本研究依据对黑龙江省部分牧场奶牛乳房炎致病菌分离鉴定以及药敏试验结果,选取盐酸吡利霉素、头孢噻呋钠和复方阿莫西林为试验药物,对患有隐性乳房炎的奶牛进行治疗并对乳品质进行跟踪监测。结果表明盐酸吡利霉素对隐性乳房炎的治愈率最高,对临床型乳房炎的治疗效果略差于复方阿莫西林,盐酸吡利雷素与复方阿莫西林对两种类型乳房炎治疗的总有效率相当,但盐酸吡利霉素对乳品质（尤其是降低体细胞数方面）的改善作用显著好于复方阿莫西林治疗组。     

A comparative randomized field trial on intramammary and intramuscular dry cow antibiotic treatment of subclinical Staphylococcus aureus mastitis in dairy cows

The efficacy of two dry cow treatment (DCT) regimens for subclinical Staphylococcus aureus mastitis was evaluated in naturally infected dairy cows. At dry-off, cows were assigned to two treatment groups by randomized blocks on the basis of parity and somatic cell count (SCC). Two antibiotic DCT regimens were used, namely: (1) a single intramammary infusion containing sodium nafcillin, procaine benzylpenicillin and dihydrostreptomycin; and (2) systemic cefquinome administered intramuscularly, twice at a 24-h interval. In the intramammary (IMM) treatment group, the S. aureus intramammary infection (IMI) rate was reduced from 40% (56/140 quarters) before dry-off to 20% (28/140) after calving. Seventy per cent (39/56) of the S. aureus-positive quarters were negative after calving, and 13% (11/84) of the negative quarters were positive after calving. In the systemic treatment group, the S. aureus IMI rate increased from 39% (29/74 quarters) before dry-off to 55% (41/74) after calving. Twenty-eight per cent (8/29) of the S. aureus-positive quarters were negative after calving and 45% (20/45) of the negative quarters were positive after calving. The odds ratio of an S. aureus-positive quarter being negative after calving in the IMM group relative to the systemic therapy group was 44.6 (95% confidence interval = 2.1-909.1, P < 0.01). Parity, quarter, milk SCC and N-acetyl-beta-D-glucosaminidase were tested in the model, and were found to have no significant effect on S. aureus cure rates or new IMI rates. The IMM treatment resulted in a higher cure rate compared with that observed in previous studies. The very low cure rate after systemic cefquinome treatment was comparable to the spontaneous cure rate observed in untreated controls in previous studies. The unfavourable results of the cefquinome systemic DCT might reflect inadequate pharmacokinetic properties of the drug regarding poor udder penetration in subclinical mastitis and short antimicrobial effect compared with the IMM treatment.     

Changes in acute-phase proteins and cytokines in serum and milk whey from dairy cows with naturally occurring peracute mastitis caused by Klebsiella pneumoniae and the relationship to clinical outcome

This study was conducted to evaluate the changes in acute-phase proteins and cytokine concentrations in dairy cows with naturally occurring peracute Klebsiella pneumoniae (K. pneumoniae) mastitis and their association with the outcome of the disease. Seventeen Holstein cows with K. pneumoniae mastitis from 8 dairy farms were divided on the basis of outcome after local and systemic therapy into 2 groups comprising 8 euthanized cows and 9 that recovered. Changes in acute-phase proteins and cytokine concentrations in cows with K. pneumoniae mastitis were evaluated at the onset of the disease (day 0) and at days 3, 7 and 14 after therapy and compared with those of 13 healthy dairy cows. The concentrations of haptoglobin (Hp) and interleukin (IL)-6 in serum and α(1)-acid glycoprotein and IL-1β in serum and whey on day 0 were significantly (P<0.05) higher in the euthanized cows than in those that recovered and the healthy cows. A correlation (r=0.90, P<0.01, n=17) was found between IL-6 and Hp concentrations in sera from recovered and euthanized cows at day 0. This indicated that serum concentrations of Hp and IL-6 at the initial examination were prognostic factors for survival, and the cutoff values were 2,020 μg/ml and 32 ng/ml, respectively. These results suggest that IL-6 and Hp concentrations are involved in the manifestation of K. pneumoniae mastitis and may be possible indicators of the prognosis of peracute K. pneumoniae mastitis.     

Effects of two anti-inflammatory drugs on physiologic variables and milk production in cows with endotoxin-induced mastitis

OBJECTIVE: To determine the effects of 2 anti-inflammatory drugs in lactating Holstein cows with endotoxin-induced mastitis. ANIMALS: 30 multiparous Holstein cows that had been lactating for 30 to 60 days. PROCEDURE: Bacterial culture of milk samples and physical examinations established that study cows were in good health and free of mastitis. Mastitis was induced in 1 front mammary gland by intramammary administration of purified bacterial endotoxin. Cows were allocated into 1 of 3 treatment groups: untreated endotoxic mastitis (n = 9), endotoxic mastitis plus flunixin meglumine (9), and endotoxic mastitis plus isoflupredone acetate (10). Heart rate, rectal temperature, mammary surface area, and rumen motility were recorded hourly for 14 hours following endotoxin administration. Flunixin meglumine or isoflupredone acetate was administered after mammary swelling and rectal temperature > or = 40 degrees C had developed. Milk production was evaluated from 5 days before to 10 days after induction of mastitis. RESULTS: Neither drug ameliorated loss of milk production or swelling of the affected mammary gland. Both drugs reduced mean heart rate during the 14 hours following endotoxin administration, compared with untreated control cows. Cows treated with flunixin meglumine had increased rumen motility and decreased rectal temperature during the same period, compared with all other cows. CONCLUSIONS AND CLINICAL RELEVANCE: Neither drug enhanced recovery of milk production following endotoxin-induced mastitis. Flunixin meglumine decreased rectal temperature, whereas isoflupredone did not; however, it has not been established that reduction of fever is beneficial to cows with naturally occurring mastitis.